Alpha Technologies Continuity: 1000_2000_3000 - Manual (Page 44)

0170009-J0 Rev B 42
A-2 Utility is Normal
When the utility voltage is normal, the AC power is rectified to DC power, which is then fed into the in-
verter. The charger is switched to charge the batteries. The inverter transforms the DC power to clean AC
power that supplies the loads. The , ,and LEDs are illuminated.
A-3 Utility Power is Abnormal/Absent
The working principle of the UPS when the utility power is abnormal is illustrated below:When the utility
power is abnormal (under voltage, over voltage or absent), the UPS converts battery power to AC power
through the DC-DC and DC-AC inverter. It also disables the AC-DC and charger sections. This happens
instantaneously as the abnormality is detected.
1. When utility power returns to normal, the UPS switches to normal mode as explained in the previous
section.
2. During a utility outage, the figure above illustrated the operation of the UPS. When the batteries are
depleted, the buzzer beeps continuously until the unit is shutdown. The UPS low battery protection
shuts off the output after a preset threshold to avoid over-draining the batteries. The
LOW
(battery
low)& (battery abnormal) symbols appear on the LCD until the UPS is completely shut off. The
UPS re-starts automatically when the utility is restored.
A-4 Overload Condition
1. Most electronic and IT equipment draw an inrush current when turned on. The amplitude and
duration of the inrush current varies depending on the equipment. Some inrush currents can be
as high as six times the rated capacity while some equipment produce negligible inrush currents.
To prevent severe inrush current damage to the inverter, the UPS is equipped with an electronic
overload protection feature. If the UPS load is between 105 and 120% of its capacity, it switches to
the bypass mode after 30 seconds to protect the inverter. If the overload condition is removed, the
UPS switches back to inverter mode. If the UPS load is more than 150% of its capacity, the inverter
shuts down immediately.
2. The UPS bypass loop is also equipped with overload protection. Its overload capacity is illustrated by
the graphs and table below.